In a process of a Hybrid Automatic Repeat Request (HARQ), a User Equipment (UE) monitors a High Speed-Shared Control Channel (HS-SCCH). If no data is received, the UE performs no action, which can be regarded as that the UE does not send information to a base station (Node B). In this case, the Node B considers that feedback information is discontinuous transmission (DTX) information. If data is received, data on a high speed-downlink shared channel (HS-DSCH) is detected according to control channel information. If the received data is correct, Acknowledgement (ACK) information is sent to the Node B. If the received data is incorrect, Negative Acknowledgement (NACK) information is sent to the Node B. The DTX, ACK, and NACK information are generally referred to as Hybrid Automatic Repeat Request-Acknowledgement (HARQ-ACK) information. The sent information is encoded and sent to the Node B through an uplink High Speed-Dedicated Physical Control Channel (HS-DPCCH). The Node B receives and decodes the feedback information. If the feedback information is ACK, new data is sent. If the feedback information is NACK, the data is retransmitted. If the feedback information is DTX, the new data is resent.
In the technology of Dual Carrier (Dual Cell)-High Speed Downlink Packet Access (DC-HSDPA), if downlink multi-carriers use two HS-DPCCH channels for feedback, a case that power is limited occurs, which influences the coverage. In order to save the power resources, in a case that the UE is not configured with Multiple-Input Multiple-Output (MIMO), a feasible technical solution is that two carriers of a dual-carrier only use one HS-DPCCH for information feedback. Thus, joint encoding needs to be performed on feedback information of the two carriers (cells). The encoding is to map various HARQ-ACK joint signals into a 0-1 sequence with 10 bits.
In Release 5 (R5) of the Technical Specification (TS) 25.212 in the 3rd Generation Partnership Project (3GPP) Protocol, an encoding scheme for a single-carrier configured with no MIMO is provided. In this case, three signals need to be fed back in total: ACK, NACK, and DTX. The ACK and NACK need to use a codeword, as shown in Table 1-1:
TABLE 1-1HARQ-ACK Encoding Scheme for Single-Carrier Configured with No MIMOACK1111111111NACK0000000000
In Release 6 (R6) of the TS25.212 in the 3GPP Protocol, a preamble (PRE) and postamble (POST) sending mode is introduced to decrease transmit power of the UE, so that two new signals PRE and POST are introduced and codewords of the two signals are further used in Release 7 (R7) and Release 8 (R8).
In R7 of the TS25.212 in the 3GPP Protocol, an encoding scheme for a single-carrier configured with MIMO is provided. The scheme includes a single stream mode and a dual stream mode, in which three signals and five signals need to be fed back respectively. The signals fed back in the single stream mode are ACK, NACK, and DTX. The dual stream mode includes a stream 1 and a stream 2, and the fed back signals can be represented in the form of “stream 1 feedback signal_stream 2 feedback signal”. Specifically, the signals fed back in the dual stream mode may be ACK_ACK, ACK_NACK, NACK_ACK, NACK_NACK, and DTX, where the DTX represents that feedback signals of the stream 1 and the stream 2 are DTX. Besides the DTX, the feedback scheme needs six codewords in total. When the PRE/POST sending mode is employed, the PRE/POST is the same as that in R6, as shown in Table 1-2.
TABLE 1-2HARQ-ACK Encoding Scheme for Single-Carrier Configured with MIMOSingle Stream Mode (1 transmission block)ACK1111111111NACK0000000000Dual Stream Mode (2 transmission blocks)Stream 1Stream 2FeedbackFeedbackSignalSignalACKACK1010111101ACKNACK1101010111NACKACK0111101011NACKNACK1001001000PRE/POST Indication InformationPRE0010010010POST0100100100
In R8 of the TS25.212 in the 3GPP Protocol, an encoding scheme for a dual-carrier configured with no MIMO is provided. The scheme needs to feed back nine signals, and eight codewords are required (the DTX does not need to use any codeword). When the PRE/POST sending mode is employed, the PRE/POST is the same as that in R6, as shown in Table 1-3:
TABLE 1-3HARQ-ACK Encoding Scheme for Dual-Carrier Configured with No MIMOThe UE only detects data blocks on a primary carrier.ACK1111111111NACK0000000000The UE only detects data blocks on a secondary carrier.ACK1111100000NACK0000011111The UE detects data blocks on the two carriers at the same time.PrimarySecondaryCarrierCarrierFeedbackFeedbackSignalSignalACKACK1010101010ACKNACK1100110011NACKACK0011001100NACKNACK0101010101PRE/POST Indication InformationPRE0010010010POST0100100100
Currently, research on a technology of combining DC-HSDPA with MIMO (DC-MIMO) has not started yet, and through research of the prior art, the inventor found that if the prior art is employed to solve a DC-MIMO problem, the most direct method is to employ two code channels, each carrier using a code channel, and then employing the encoding scheme as shown in Table 1-2 to each carrier. This method needs to consume too much of the power that is configured to feed back HARQ-ACK signals. Usually, the consumed power doubles that consumed by the single-carrier and a system cubic metric (CM) value is increased, which affects performance of the system.